In recent years, it has become important to protect the consumer from unknowingly purchasing a tamper damaged product. Products packaged in reclosable container assemblies are especially vulnerable to tampering because a closure member can be removed in the store and subsequently replaced, thereby concealing the fact that entry to the container has occurred. The problem of undetected entry into a closed reusable container has led to the development of plastic containers and caps for food and other consumable products wherein a plastic closure cap is provided having a tear strip which must be removed the first time the container is opened. With round containers, very effective tamper indicators have been provided on the tear strip to provide an indication when an attempt at tampering is made without removal of the tear strip. U.S. Pat. Nos. 4,682,706 to F. DeVore et al. and 5,042,680 to M. Argudo et al. disclose tamper indicating tear off strips which include a plurality of spaced apart grooves formed in the tear off strip which extend upwardly from the lower edge of the strip and which are bridged by a thin membrane. This membrane tears if an attempt is made to insert an object under the tear off strip.
Many powdered products, such as cocoa and flour, are packaged in substantially rectangular containers having long, curved sidewalls and short straight endwalls joined by arcuate corners. In the past, rectangular containers have been provided with removable lids, as disclosed by U.S. Pat. Nos. 2,941,562 to Ripin and 4,488,676 to Halliday, but these lids are not tamper evident and the container-lid assemblies do not provide features, such as air venting, which are desirable in rectangular containers for powdered food products. Particularly in a plastic container, if a venting system is not provided to equalize pressure in the container with external pressure, the container walls will bulge and may cause a cap seal to rupture.